Organic polymeric structure having an ultraviolet light absorbent compound incorporated therein



y 1962 L. E. AMBORSKI 3,043,709

ORGANIC POLYMERIC STRUCTURE HAVING AN ULTRAVIOLET LIGHT ABSORBENTCOMPOUND INCORPORATED THEREI Filed July 18, 1958 FIG. 1

PARTICLES OF ULTRAVIOLET LIGHT ABSORBENT COMPOUND.

ORGANIC POLYIIERIC FILI I.

FIG- 2 PARTICLES OF ULTRAVIOLET LICIIT ABSORBENT COMPOUND.

ORGANIC POLYMERIC FILM.

PARTICLES OF ULTRAVIOLET LICHT ABSORBENT COMPOUND.

INVENTOR LEONARD E. AMBORSIII ATTORNEY completely successful.

United States Patent 3,043,709 ORGANIC POLYMERIC. STRUCTURE HAVING ANULTRAVIOLET LIGHT ABSORBENT COM- POUND INCORPORATED'THEREIN LeonardEdward Amborski, Bulfalo,-'N.Y., assignor to E. I. du Pont de Nemoursand Company, Wilmington, Del., acorporation of Delaware Filed July 18,1958, Ser. No. 750,068

20 Claims. (Cl. 117-7) This invention relates to organic polymericstructures and particularly to polymeric films suitable for outdoor use.a

It is well known that organic polymeric structures such as structures ofpolyethylene terephthalate, polyethylene, polyoxymethylene, celluloseacetate, polyvinyl chloride, polyvinyl fluoride, etc., when subjected tosunlight, deteriorate rapidly. The ultraviolet rays present in sunlighttend to embrittle the structures and reduce the level of their physicalproperties substantially.

The use ofcertain chemical compounds as ultraviolet light absorbers isalso well known. Heretofore these compounds have either beenincorporated into the polymer melt prior to forming the structure orthey have been coated on the surface of the polymeric structure. Thefirst method, incorporating the compound in the melt, distributes thecompound throughout the structure. This procedure is both uneconomicaland, more important, not Much of the harmful radiation penetrates anddeteriorates the structure before reaching the too well-distributedabsorber. Concentrating the screening agent or absorber on the surfaceof the struc: ture as in the second method, the coating method, offersmuch more effective protection. However, difliculties are usuallyencountered in adhering the coatings to the surface of the structure.The coatings may not adhere well, or if they do adhere, they oftencannot be applied without forming streaks. Furthermore, the coating,which usually contains a polymeric material, may also tend to bedegraded by ultraviolet light and .peel from the base structure. I

It is an object of this invention to provide Weather-resistant organicpolymeric shaped structures, particularly films suitablelfor outdooruse. It is a further object to provide a process for incorporatingultraviolet absorbent compounds into the polymeric structure so that thecompounds are concentrated uniformly at the surface of the structure andare firmly attached to the structure. Other objects will appearhereinafter.

Theobjects are accomplished by a process which com prises applying anultraviolet light absorbent compound;

having a melting point lower than the melting point'of the basestructure and being compatible therewith to' the surface of a basestructure, and then heating the structure to a temperature above themelting point of the ultraviolet light absorbent compound and below themelting point of the base structure. I i

The invention will be .more clearly understood by referring to thefollowing detailed description in conjunction with the drawings, inwhich:

FIGURE 1 illustrates one embodiment of the present invention; and 7FIGURE 2 illustrates another embodiment of the present invention.

InFIGURE 1 is illustrated an organic polymeric film of the presentinvention that is Weather-resistant (resistant to degradation byultraviolet light) for exposure of one surface. Reference numeral 11represents the film and reference numeral 12 represents the particles ofultraviolet light absorbent compound distributed adjacent to the surfaceof the film. The concentration of particles, as shown in FIGURE 1, is amaximum adjacent to the surface and ice decreases substantially to ierowithin a distance of no greater than about 20% of the thickness of thefilm. For the results of the present invention, it is necessary todistribute the ultraviolet light absorbent compound within the limits ofthe aforementioned depth to the extent of at least 0.4 gram per squaremeter of the film. Thus, the

remaining thickness of the fiim, at least 80%, is substantially free ofparticles. In the case of polymeric film it is preferred to maintain theultraviolet light absorbent compound substantially completely within adistance of 0.1 mil (.0001 inch) of the surface. Therefore, thepreferred minimum thickness of the polymeric film of the presentinvention is 0.5 mil (.0005 inch).

FIGURE 2 illustrates a film that is weather-resistant for exposure ofboth surfaces. The ultraviolet light absorbent particles 12 aredistributed adjacent to both surfaces. .The same limitations, asmentioned previously, prevail for this film. The concentration adjacentto each surface is 0.4 gram per square meter, of the film and is limitedsubstantially to no greater than 20% of the thickness adjacent to eachsurface. Thus, at least 60% of the thickness at the center issubstantially free of particles. For the preferred film having a minimumthickness of 0.5 mil, the particles are limited to substantially 0.1 milfrom each surface of the film, i.e., atotal of 0.2 mil of the filmthickness.

:The invention will be described for organic polymeric films,particularly polyethylene terephthalate film. Howdetermined by thefollowing test. 'A solution of the ultraviolet light absorbent compoundis applied to the surface of a base film of known weight. The solvent ispermitted to evaporate leaving a coating of approximately -1 gram of theabsorber per square meter of film. The coated film is heated for /2 to 1hour at a temperature between the melting points of the absorber and thebase film. The resulting film is Weighed to determine how much of thecompound has'been absorbed. It is then dipped twice, each time for 5seconds, in a solvent for the absorber. After drying, the film isweighed again. If no substantial weight is lost by dipping, theultraviolet light absorbent compound is deemed compatible with the basefilm.

The ultraviolet light absorbent compound useful in the presentinvention, besides being compatible with the base film and having amelting point below thatof the'base film, must also:

(1) Have a high absorptive capacity for light in the ultraviolet range(wave lengths of 200-400 millimicrons) and transmit no more than 10% ofthe light at a wave length of 390 millimicrons.

(2) Be able to dissipate absorbed energy in a manner that neitherphysically damages norv colors the base polymeric fihn.

(3) Be stable against destruction by absorbed energy.

(4) Resist the action of water.

(5) Be substantially free from odor and color.

The most important compounds fulfilling the above'requirements aresubstituted benzophenone derivatives having the formula wherein X X andX are selected from the group consisting of hydrogen, hydroxy, alkyl,alkoxy and halogen. Thepreferred substituted benzophenone derivativesinclude 2,2 dihydroxy 4,4 dimethoxybenzophenone;

2,2,4,4'-tetra.hydroxybenzophenone; 2-hydroxy 4,4 dimethoxybenzophenone;2,4-dihydroxybenzophenone; 2-hydroxy 4 methoxybenzophenone; 2,2dihyd'roxybenzophenone; and 2,2'-dihydroxy-4,4'-diethoxybenzophenone.The most outstanding is a mixture of benzophenone derivatives known asUvinul 490. These compounds are compatible with substantially all theuseful organic polymeric films and, having melting points between 120and 170 C., melt at temperatures substantially below the useful organicpolymeric films.

The process of the invention involves applying the ultraviolet lightabsorbent compound to the base film in one of a variety of methods. Thecompounds may be applied from a solution; from a dispersion such as adispersion in water; as a solid in the form of a powder or dust; or as aliquid in the form of a melt.

In the next step, the coated film is heated to 'a temperature above themelting point of the absorber and below the melting point of the basefilm. In the case of the substituted benzophenone derivatives, thistemperature may be anywhere from about 115 C. to about 200 C.

The exposure time used in this step need only be long enough for thecompound to be absorbed into the film surface. For the substitutedbenzophenone derivatives, the exposure time may vary from 15 seconds to30 minutes, preferably at least '2 minutes, depending upon theparticular benzophenone derivative, the base film, the coating weight,the particular temperature selected, etc. A coating weight of at least0.4 gram per square meter has been found most desirable when using thesubstituted benzophenone derivatives. Improvement may be ob tained byincreasing coating weights to a weight of approximately gram per squaremeter. Although coating weights greater than 1.0 gram per square metercan be used, they are not necessary in the present invention.

The invention will be more clearly understood by referring to thedescriptive material and the examples which follow. It is understoodthat the examples, although illustrating specific embodiments of thepresent invention, should not be considered limitative. Because of thecommercial importance and the widespread use of polyethyleneterephthalate film in outdoor applications, the description of theinvention will mostly concern treating polyethylene terephthalate film.

The untreated polyethylene terephthalate film may be prepared in themanner described in U.S. Patent 2,465 ,3 19 to Whinfield and Dickson, bythe condensation of ethylene glycol and terephthalic acid, preferably byan ester interchange between ethylene glycol and a dialkyl esterterephthalic acid such as dimethyl terephthalate. Of particular interestis oriented, heat-set polyethylene terephthalate film which is preparedby stretching and/or rolling the film in two directions to at least 2times, preferably 2.5 to 4 times, the original dimensions of the filmand then heating the film to an elevated temperature of about 150-250 C.while restricting dimensional change, usually by holding it undertension. The oriented, heat-v set polyethylene terephthalate film isclear, impact resistant, insensitive to moisture, tough and very strong;in short, the film possesses most of the physical and chemicalproperties that make it ideal for glazing and other outdoorapplications. With the present invention which imparts resistance todegradation by ultraviolet light, the film is virtually ideal for theaforementioned purposes.

The invention is also applicable to most non-fibrous and fibrousflexible, transparent, organic, polymeric sheet materials and to moldedarticles of polymeric materials. Such polymeric materials include thecellulosic materials such as regenerated cellulose, hydroxyethylcellulose, carboxymethyl cellulose, amylose, cellulose acetate, ethylcellulose, cellulose nitrate; polyethylene, polyoxymethyl- 1A mixture of2,2-dihydroxy-4A'-dimethoxybenzophenone and2,2,4,4-tetrahydroxybenzophenone, manufactured by General Aniline andFilm Corp.

' year.

11'. ene, polyvinyl chloride, polyvinyl fluoride, etc. or films. andfabrics formed from mixtures of these or films and fabrics coated withany of these materials.

EXAMPLES IV Polyethylene terephthalate film was oriented by stretchingin two directions to 3 times its original dimensions. The oriented filmwas then heat-set by heating it to a temperature of 220:5 C. whileholding the film under tension. The polyethylene terephthalate film, 5mils (.005 inch) thick, was cut into 10" x 10" sheets and weighed.

The sheets were dipped into a solution of about 5% Uvinul 490 in methylethyl ketone. The solvent evaporated quickly leaving a thin, evenlydistributed Uvinul 490 coating which was tacky.

The samples were heated in an oven maintained at a. temperature of 130-*-15 C. After 30 minutes the surface of the film was smooth and dry,essentially the same as untreated film. The treated samples were weighedto determine the amount of Uvinul 490 that had been absorbed by thesamples.

The samples were exposed to Florida sunshine on an, open frame rack atan angle of 45 facing south for one,

A comparison of the physical properties of polyethylene terephthalatefilm coated with from 0.1 to 2.45 grams per square meter prior to andafter exposure are. presented in Table 1.

In this table and subsequent tables of the specification, threeproperties are usedto determine the extent of degradation caused byultraviolet light. Tensile strength and elongation are well known tothose skilled in the art and are measured in the conventional manner.Intrinsic viscosity is a measure of the degree of polymerization and isdefined as the limit of v/ C as C approaches zero, where v=(viscosity ofsolution of polymer in a phenol-tetrachloroethane solventviscosity of'solvent)/viscosity of solvent. By plotting several values of v/C versusC and extrapolating to zero concentration, the intrinsic viscosity isobtained. A decrease in this value indicates the occurrence ofdegradation.

Table 1 PHYSICAL PROPERTIES OF FILMS OF INVENTION COMPARED TO A CONTROLWeight of Tensile strength Percent elon- Intrinsic visabsorber (lbs/sq.in. x 10- gation cosity Ex. (gram/sq.

meter) Initial 1 year Initial 1 year Initial 1 year 0 23. 7 1.0 118 0.57 0. 40 0.2 i. 1 23. 0 l6. 6 110 2G 0 57 0. 49 0.3 i. 1 23. O 17.5 11030 0.57 0. 50 0. 5 i. 05 23. 0 23.0 110 0. 57 0. 54 l. 1 i. 06 23.0 22.9 108 0. 57 0. 54 2. 25. 2 23.0 23. O 110 110 0.57 0.55

In the following three examples, Examples VI-VII, an acceleratedweathering test was used. Samples prepared in the manner described forExample I were placed in a constant temperature box which was maintainedat 55 C. These samples were exposed while on a 33 /3 revolutions perminute turntable to the ultraviolet light produced by five WestinghouseFS-ZO-T-IZ fluorescent sun lamps.

EXAMPLE VI An oriented, heat-set polyethylene terephthalate film,

5 mils (.005 inch) thick, was treated as in Example I to contain 2.3grams per square meter of Uvinul 490. In

the accelerated weathering test this sample remained clear and toughafter 8,254 hours of exposure compared to an untreated control whichdegraded substantially after 200 hours of exposure.

EXAMPLE VII Oriented, heat-set polyethylene terephthalate film samples,1 mil (.001 inch) thick, were treated as in Example I to contain0.56-0.75 gram per square meter of Uvinul 490. In the acceleratedweathering test these samples remained clear and tough after an averageof 5,000 hours of exposure compared to an untreated control whichdeteriorated completely after 116 hours of exposure.

EXAMPLE VIH An oriented, heat-set polyethylene terephthalate film,

, 0.5 mil (.0005 inch) thick, was treated as in Example I to contain .65gram per square meter of Uvinul. 490. In the accelerated weathering testthis sample remained clear and tough after 1,296 hours of exposurecompared to an untreated control which deteriorated completely after 54hours of exposure.

EXAMPLES IX-XI In these examples, a melt-printing procedure was used toapply the ultraviolet light absorbent compound to an oriented, heat-setpolyethylene terephthalate film. The film, mils (.005 inch) thick, wasunwound at a speed of 40 feet per minute into the nip of two rolls. Thelower, smooth surfaced print roll was an internally oilheated,chromium-plated roll which'dipped into a pan of molten Uvinul 490. TheUvinul 490 was maintained at a temperature between 115 and 120 C. Adoctor knife was placed in position to remove the excess Uvinul 490picked up by the roll. The upper roll was a rubber back-up roll. Afterpassing through the nip of these rolls and past the doctor knife, thecoated web was led through a 24-foot dryer whose temperature wasmaintained between 150 and 165 C.

For Examples X and XI, a similar procedure was used for oriented,heat-set polyethylene terephthalate films of thicknesses of .003 inchand .001 inch, respectively. The properties of the resulting films overa six-month period of exposure to Florida sunshine compared to untreatedcontrols are presented in Table 2..

Table 2.

6 compared to an untreated control which deteriorated after 116 hours.

' EXAMPLES XIII-XV In these examples, oriented, heat-set polyethyleneterephthalate film was treated with a solution of Uvinul 490 by means ofa dip-doctor roll procedure. The film, 5 mils .005 inch) thick forExample XIII, was unwound from a storage roll and led over a guide rollinto a dip tank. After passing around a dip bar submerged in the tank,the film passed between the nip of two doctor rolls above the tank whichserved to remove excess solution from the surface of the web and tosmooth the remaining solution over the surface. The treated web was thenled through a drying tower maintained between a temperature of 135 C. atthe entry to about 90 C. near the exit. The web speed was 34 feet perminute; the heattreating time was two minutes; and the concentration ofthe solution was 3.3% Uvinul 490 in methyl ethyl ketone.

For Examples XIV and XV, oriented, heat-set polyethylene terephthalatefilms having thicknesses of .003 inch and .001 inch, respectively, wereused. The proper: ties of the resulting films after a six-month periodof exposure to Florida sunlight compared tountreated controls arepresented in Table 3.

Table 3 PHYSICAL PROPERTIESOF FILMS OF INVENTION COM- PARED TO CONTROLSPHYSICAL PROPERTIES OF FILMS OF INVENTION COMPARED TO CONTROLS Weight ofTensile strength Percent elongation Intrinsic viscosity absorber(lbs./sq.1n. x 10- Example (gram/3 me er V Initial 1 mo. 3 mo. 6 mo.Initial 1 mo. 3 mo. 6 mo. Initial 1 mo. 3 mo. 6 mo.

Control C 0 21. 1 l3. 0 l 0 1 0 106 3 1 0 1 0 0. 56 0. 385 1 0 1 Q 1Deteriorated completely-These films were so brittle that they brokebefore testing,

' EXAMPLE x11 In this example the solution-printing procedure was usedto apply the'ultraviolet light absorbent compound to oriented, heat-setpolyethylene terephthalate film varying in thickness from .005 inch to.0075 inch. The equipment was substantially the same as described forExample IX. The print roll was dippedinto a pan containing a 25%solution of Uvinul 490 in methyl ethyl ketone. Both the roll and thesolution of Uvinul '490 were unheated. A doctor knife was used to removeany excess Univul 490 solution picked upby the roll. The-coated Web wasthenpassed through a dryer maintained at a temperature between 180 and190 C. The web speed varied from 33-107 feet per minute depending on thethickness of the film. The'amount of Uvinul 490 retained by thepolyethylene, terephthalate film was 057 gram per square meter. Theresulting film was clear and had a good appearance. In the acceleratedweathering test, the fi-lm deteriorated after 2,088 hours of exposureEXAMPLES XV I-XVIII ethylene terephthalate film were dipped into asolution of fUvinul 490 in methyl ethyl ketone. The solution wasmaintained at an elevated temperature to cause the ultraviolet lightabsorbent compounds, Uv-inul 490, to penetrate the surface of the film.The film thickness inExample XVI was .005 inch;in Example XVII, .003inch; and in Example XVIII, .001 inch. The coating weights of thesamples were varied as shown in Table 4 by changing the solutiontemperature from C. to- C.; the dip time from 30 seconds to 90 seconds;and the concentration of the solution between 3% and 11%.

The physical properties of the treated film samples were averaged andare compared to the properties of untreated controls over a period ofsix months exposure to Florida sunshine in Table 4.

Table 4 PHYSICAL PROPERTIES OF FILMS OF INVENTION COMPARED TO CONTROLSWeight of Tensile strength Percent elongation Intrinsic viscosityabsorber (lbs./sq.in. x 10- Example (gram/sq.

meter) Initial 1 mo. 3 mo. 6 1110. Initial 1 mo. 3 mo. 6 mo Imtial 1 mo.3 mo. 6 mo.

XVL- 0. 46-0. 79 26. 8 20. 1 l9. 5 25. 8 119 56 69 109 0. 55 0. 59 0. 550. 42 Control A. 27.0 14. 2 12. 6 0 120 7 2 0 0. 55 O. 495 0. 48 0. 35XVII 0. 43-0. 75 31. 2 21. 9 25. 8 24. 4 134 58 108 74 0. 56 0. 60 0. 570. 53 Control B 0 30. 2 19. 2 16. l 0 132 44 0 0.56 0.485 0.41 0. 36 III0. 43-0. 63 25. 7 17. 4 17. 1 15. 6 121 17 36 34 0. 53 0.50 0. 51 0.48

Control 0...- 0 21. 1 13. 0 0 0 106 3. 0 0 0 0.56 0.385 0 0 EXAMPLE XIXAn aqueous dispersion was prepared by ball milling for 16 hours thefollowing ingredients:

30 parts of 2,2-dihydroxy-4,4'-dimethoxybenzophenonc 55 parts of waterparts of Blancol 1 The dispersion was diluted further with about 500parts of Water to provide a dispersion containing about 5% of thebenzophenone.

Samples of oriented, heat-set polyethylene terephthalate film, .005 inchthick, were dip-coated with the dispersion and then heated to atemperature of 135-l45 C. for a period of two minutes. Excess absorberwas washed from the film surface with distilled water.

The film, containing 0.4 gram per square meter of the absorber on eachside, was tested by measuring the intensity of the light transmittedthrough the film. Sub- 'stantially all light below a wave length of 390millimicrons was screened out by the absorber and was not transmittedthrough the film.

EXAMPLE XX Example XIX was repeated substituting Uvinul 490 for2,2-dihydroxy-4,4-dimethoxybenzophenone in the previous dispersion. Theresults were identical. Substantially all ultraviolet light was screenedout by the use of 0.5 gram of Uvinnl 490 per square meter on each sideof the oriented, heat-set polyethylene terephthalate film. It was alsonoted that 77% of the Uvinul 490 was removed by scraping off 0.1 milfrom each surface.

EXAMPLE XXI Samples of cellulose acetate film, 1.2 mils (.0012 inch or120 gauge) thick, were dipped into a 2%% solution of Uvinul 490 inethanol. The samples were dried at room temperature, then heated in anoven for 30 minutes at 130 C. The samples, containing an average of 1.1grams of absorber per square meter (total for both sides), were giventhe accelerated weathering test as described in Examples VI-VIII. Thetreated samples endured an average of 1,110 hours before cracking orcreasing compared to an average of 170 hours for untreated controlsamples.

EXAMPLE XXII EXAMPLE XXIII Samples of polyvinyl chloride film, 1 mil(.001 inch) A Wetting agent manufactured by Antara Chemical Corp.

thick, were dipped into a 2 /2% solution of Uvinul 490 in ethanol. Thesamples were then dried at room temperature and heated in an oven for 30minutes at C. The samples, containing an average of 1.1 grams ofabsorber per square meter (total for both sides), next underwent theaccelerated weathering test as described previously. The treated samplesendured an average of 900 hours before failure as indicated by loss ofelongation compared to an average of 220 hours for untreated controlsamples.

EXAMPLE XXIV Samples of polyvinyl fluoride film, 0.001 inch thick, weredipped into a solution containing 25 parts Uvinul 490, 25 parts benzene,and parts methyl ethyl ketone. Polyvinyl fluoride film had been preparedin accordance with procedures described in US. Patent 2,419,010. Excesssolution was wiped from the film and the film was dried. Heating thecoated film for two minutes in an oven at C. caused the ultravioletlight absorbent compounds to penetrate the surface. The film samples,containing an average of 0.8 grams of absorber per square meter, weresubjected to the accelerated weathering test as described previously.The treated samples endured an average of 5,600 hours before failurecompared to an average of 2,300 hours for untreated control samples.

EXAMPLE XXV This example illustrates most vividly the important aspectsof the present invention. Polyethylene terephthalate films prepared inaccordance with the present invention are compared with three controls:

Control Apolyethylene terepht-halate film having the ultravioletabsorber incorporated throughout the polymer;

Control B-polyethylene terephthalate fihn having the ultravioletabsorber in a polymeric composition coated on the film;

Control Cuntreated polyethylene terephthalate film, oriented andheat-set as described hereinafter.

In this example, 0.005 inch thick polyethylene terephthalate film,oriented by stretching 3 X in both directions and heat-set at 200 C.,was surface-penetrated with Uvinul 490. A 2.2% Uvinul 490 solution inmethyl ethyl ketone was applied to the film in the manner described inExample I. The film was air dried and then heated in an oven atatemperature of l30150 C. for 30 minutes. The film had an absorberweight of 0.7 gram per square meter penetrated into the surface on eachside of the film.

The fihn of the invention was compared to the several controls afterthey had been exposed to Florida sunshine over a period of 18 months.The results are given in Table 5 Control A was prepared in a laboratoryautoclave in accordance with the process described in US. Patent2,465,319 :to Whinfield and Dickson. 0.62% Uvinulf 490 was added to thepolymer mixture before substantial polymerization had taken place. Thefinished polymer was extruded in the form of a film, quenched andsubsequently oriented by stretching the film in both the longitudinaland transverse directions to an extent of 3 times its initial length.The fihn was then heat-set under 9 tension at 200 C. The film contained1.09 grams of absorber per square meter.

Control B was prepared by coating oriented, heat-set, polyethyleneterephthalate film with a cellulose acetate butyrate coating compositioncontaining 30% Uvinul 490 from a solution in methyl ethyl ketone.

EXAMPLE XXVII Samples of polyoxymethylcne which had been colored red,yellow, and pastel green and blue were fabricated into bars 5" x /2 x/s". One-half of the long portion of these colored bars were treated bythe process described in Example XXVI, and the bars were subjected to300 Table 5 PHYSICAL PROPERTIES OF FILM OF INVENTION COMPARED TOCONTROLS Tensile strength (lbs./sq.i.n. x 10- I Percent elongationIntrinsic viscosity Example Initial 3 mo. 6 mo. 12 mo. 18 mo. Initial 3mo. 6 mo. 12 mo. 18 1110. Initial 3 mo. 6 mo. 12 mo. 18 mo.

XXV 20.0 19. 18. 7 85 80 75 0. 54. 0. 51 Control A 20. 0 14. 4 11. 911.0 86 20 4 0.53 0. 49 Control B 19. 0 20.0 9. 5 58 6D 5 r 0. 56 0. 560. 36 Control C 21. 9 5. 2 n 5.0 0 82 2 1 0 0. 55 0. 47 0. 39 L EXAMPLEXXVI This example shows the effectiveness of the process of thisinvention as applied to shaped structures of high molecular weight.polyoxymethylene. Uncolored polyoxymethylene having a number averagemolecular weight of about 40,000 was fabricated into bars 5" x /2" 11%".The bars were immersed in molten P-35 2 for a few min utes, dried at 150to 165 C., and subjected to the accelerated weathering test. Thesamples-endured an average of 2000 hours before any haze, which could bedetectable by the unaided eye, developed on the surface of the bars.

.As a control, 1 part by weight of P-35 was incorporated throughout 99parts by weight of the above-described polyoxymethylene. The mixture wasfabricated into similar bars, 5" x /2" x /a. These bars, upon beingsubjected to the accelerated weathering test, developed a surface hazeafter 500 hours of exposure.

Bars of polyoxymethylene, which did not contain any ultraviolet lightabsorbent compound, developed a surface haze between 50-100 hours in theaccelerated'weathering test.

To determine the effectiveness of the process in achieving penetrationof ultraviolet light absorber into the polymer product, thepolyoxymethylene was fabricated into blocks 1" x. 1" x 1%". The blockswere treated with P-35 by the technique described above. One mil slices,were successively removed from one sideof'each block, and the averageconcentration of P-35 in each slice was measured to determine the totalamount of P-35 which had been absorbed, and to determine the depth towhich the P-3S had penetrated.

It was found that approximately 1.4 grams of P-35 had been absorbed persquare meter of surface area of the blocks as originally treated, andthat the P-35 had penetrated approximately 2% of the total depth of theblocks. The following table shows the average concentration of the P-35as successive cuts were removed from the surface of the blocks.

Table 6 Total depth of out Concentrainto sample 81 b 'Ihclfiness 01f1P-5 in ice num er 0 s 'ce s cc per- (mils) cent by g g gg weight)Expressed g g 111 111115 depth of sample 2 2hydroxy-4methoxyt'-chlorobenzophenone, manufactured by General Anilineand Film Corp.

hours exposure at accelerated Weathering conditions. The treated halvesof the bars showed no color change that could be detected by the unaidedeye, while th untreated halves showed severe crazing.

The importance of the surface penetration technique to obtain at leastabout 0.4 gram per square meter of the ultraviolet light absorbentcompound into the surface of the organic polymeric structure isillustrated by the foregoing examples. The outstanding results obtainedwith a heat-set polyethylene terephthalate fihn oriented in bothdirections is apparent from the examples. It should be mentioned thatthe ultraviolet light ab sorbent compound can be applied and made topenetrate the surface of such a film, not only after biaxial orientationand heat-setting have been performed, but during the formation of such afilm. For example, an unoriented or unidirectionally stretchedpolyethylene terephthalate film may be treated with the absorber andheated to cause penetration, and thereafter the unoriented film may bestretched in two directions and heat-set or the one-Way stretched filmmay be stretched in the other direction and heat-set. To obtain theultimately desired Weight in the final product, a greater than normalamount of the absorber would be applied initially in both these cases.

The most useful absorbers are the substituted benzophenone derivativesof the formula wherein X X and X, are selected from the group consistingof hydrogen, .hydroxy, alkyl, alkoxy and halogen, as disclosedpreviously. A list of others that are considered useful in the processof the present invention follows:

2,2'-dihydroxybenzophenone; 2,2,4,4-tetrahydroxybenzophenone;2,2-dihydroxy-4,4'-dimethoxybenzophenone;2,2-dihydroxy-4,4'-diethoxybenzophenone;2,2-dihydroxy-4,4-dipropoxybenzophenone;2,2-dihydroxy-4,4-dibutoxybenzophenone;2,2-dihydroxy-4-methoxy-4-ethoxybenzophenone;2,2-dihydroxy-4-methoxy-4'-propoxybenzophenone;2,2-dihydroxy-4-methoxy-4t-butoxybenzophenone; 2,2-dihydroxy-4ethoxy-4'-propoxybenzophenone;2,2'-dihydroxy-4-ethoxy-4'-butoxybenzophenone;2,3-dihydroxy-4,4'-dimethoxybenzophenone;

2-hydroxy-4,4',5-trimethoxybenzophenone; 2-hydroxy-4,4,6-tributoxybenzophenone; 2-hydroxy-4-bu'toxy-4f,5'-dimethoxybenzophenone;2-hydroxy-4-ethoxy-2',4'-dibutylbenzophenone;2-hydroxy-4-propoxy-4,6'-dichlorobenzophenone; 2-hydroxy-4-propoxy-4'6'-dibromobenzophenone; 2,4-dihydroxybenzophenone;

Z-hydroxy-4methoxybenzophenone; 2-hydroxy-4-ethoxybenzophenone;2-hydroxy-4-propoxybenzophenone; 2-hydroxy-4-butoxybenzophenone;2-hydroxy-4-methoxy-4'-methylbenzophenone;2-hydroXy-4-methoxy-4-ethylbenzophenone;2-hydroxy-4-methoxy-4'-propylbenzophenone;2-hydroxy-4-methoXy-4'-butylbenzophenone;2-hydroxy-4-methoxy-4'-tertiary butylbenzophenone;2-hydroxy-4-methoxy-4'-chlorobenzophenone;Z-hydroxy-4-methoXy-2'-chlorobenzophenone;2-hydroxy-4-methoxy-4'-bromobenzophenone;2-hydroxy-4,4-dimethoxybenzophenone;2-hydroxy-4,4'-dimethoxy-3-methylbenzophenone;2-hydroxy-4,4'-dimethoxy-Z-ethylbenzophenone;2-hydroxy-4,4',5"-trimethoxybenzophenone;2-hydroxy-4-ethoxy-4-methylbenzophenone;2-hydroxy-4-ethoXy-4-ethylbenzophenone;2-hydroxy-4ethoXy-4'-propylbenzophenone;2-hydroxy-4-ethoxy-4'-butylbenzophenone;2-hydroxy-4-e-thoxy-4'-methoxybenzophenone;2-hydroXy-4,4'-diethoxybenzophenone;2-hydroxy-4-ethoXy-4-propoxybenzophenone;2-hydroxy-4-ethoxy-4'-butoxybenzophenone;2-hydroxy-4-ethoxy-4-chlorobenzophenone;2-hydroXy-4-ethoXy-4-bromobenzophenone,

and the like.

From this illustration of representative compounds, it is apparent thatthe 3, 4, 5, 6, 2', 3, 4', 5 and 6' positions in the above structuralformula may be unsubstituted or there may be eitherone or twosubstituents from the various categories mentioned previously. Thesesubstituents include methyl, ethyl, propyl, butyl, methoxy, ethoxy,propoxy, butoxy, or hydroxy radicals or a chlorine, bromine, iodine orfluorine atom.

Other ultraviolet light absorbent compounds besides the substitutedbenzophenone derivatives which are useful in the present inventioninclude the chrome complex of p-aminobenzoic acid, phenyl salicylate,resorcinol and substituted benzotriazoles.

The shaped articles of the present invention, particularly those whereinan oriented, heat-set polyethylene terephthalate film is the base film,maybe used in a multitude of outdoor applications. Among theseapplications are as plastic glazing materials for use in farm buildings,warehouses, greenhouses, radomes, potting beds, chicken coops, temporaryliving quarters, perforated window screens, coverings to replace storagestructures, e.g., silos, etc.; as glass replacement materials insemi-permanent light-weight aluminum type storm windows, windows forconvertible automobiles, trailers, portable windows for marine use,aircraft, outdoor telephone booths; in laminations to other materialssuch as plywood, aluminum, steel, fabrics, etc., used for outdoorfurniture, outdoor signs, awnings, Venetian blinds, automobile trim,automobile convertible tops, traffic markers, automobile accessories,wrapping for electric wires for outdoor use, etc.; as transparent coversfor farming purposes such as hot caps for plants, vegetables and othercrops to afford protection from frost, wind, hail, etc., protectivecoverings and tarpaulins for boats, automobiles, motorcycles and othervehicles, athletic fields, covering for airplane wings and fuselage,coverings for growing bananas, fumigation blankets for killing insectsand bacteria in the soil, ground coverings for mulching, tree trunk wrapto exclude boring insects, liners for water storage ponds, tank linersand crop covers for hydroponics farming installations, protectiveshrouds for outdoor depot-type stock pilings, automobile tire wrap,etc.; as lining materials for irrigation ditches, rain gutters, pipe andwire Wrap, outdoor pools and tanks, marine cordage, high altitudeballoons, boat sails, etc.; as packaging or wrapping material where thematerial Wrapped is subjected to outdoor weather conditions and othercorrosive attack, such as protective coverings for plastic foamstructures of all 12 varieties, fabrics for harvesting sacks, etc.; asfabric replacement materials such as upholstery material in converticleautomobiles, fabric for umbrellas and miscellaneous rainwear, beachsandals, beach umbrellas, material for outer wear, window shades, liferafts, life jackets, etc.; as tubing for hoses, ground sprinkles, etc.and in the form of molded articles to be subjected to outdoor weatherconditions.

While the invention contemplates the use of ultraviolet light absorbersas the essential addition to the base structures, other ingredients maybe added if desired. The addition of pigments, dyes, delusterants,fillers, binders, plasticizers, etc., is therefore understood to 'bewithin the purview of this invention. The films of the present inventionmay also be successfully metallized. Preferably, the film issurface-penetrated with the ultraviolet light absorbed on one side ofthe film and then metallized on the other side. Thus, metallized filmuseful for protective and decorative purposes may be made resistant toultraviolet light. Such metallized films may used in automobiledecorative applications such as eX- terior decorative panels and roofsurfaces, decals for outside use as in gasoline pumps, exterior signs,outdoor furniture and in decorative panels for machines used outsidesuch as soft drink or cigarette dispensing ma chines.

This application is a continuation-in-part of my copending applicationSerial No. 675,683, filed August 1, 1957 now abandoned.

As many widely different embodiments may be made without departing fromthe spirit and scope of this invention, it is understood that theinvention is not limited except as defined in the appended claims.

What is claimed is:

1. An organic polymeric shaped structure having accumulated therein andadjacent to at least one surface thereof to a penetration of not morethan about 20% of the cross-section of said structure from said surface,at least 0.4 gram of an ultraviolet light absorbent compound per squaremeter of surface of said structure, said compound being compatible Withsaid structure and having a melting point below that of said structure.

2. An organic polymeric film at least 0.5 mil thick having accumulatedtherein and adjacent to at least one surface thereof to a depth of notmore than about 0.1 mil from said surface, at least 0.4 gram of anultraviolet light absorbent compound per square meter of surface of saidfilm, said compound being compatible with said film and having a meltingpoint below that of said film.

3. An organic polymeric shaped structure having accumulated therein andadjacent to at least one surface thereof to a penetration of not morethan about 20% of the cross-section of said structure from said surface,at least 0.4 gram per square meter of surface of said structure of asubstituted benzophenone derivative having the formula wherein X X and Xare each selected from the group consisting of hydrogen, hydroxy, alkyl,alkoxy and halogen.

4. A product as in claim 3 wherein the organic polymeric shapedstructure is polyethylene terephthalate filrn.

5. A product as in claim 3 wherein the organic polymeric shapedstructure is oriented, heat-set polyethylene terephthalate film.

6. A product as in claim 3 wherein the organic polymeric shapedstructure is polyvinyl chloride film.

7. A product as in claim 3 wherein the organic polymeric shapedstructure is polyvinyl fluoride film.

wherein X X and X are each selected firom the group consisting ofhydrogen, hydroxy, alkyl, alkoxy and halogen.

11. An organic polymeric film at least 0.5 mil thick having accumulatedtherein and adjacent to at least one surface thereof to a depth of notmore than about 0.1 mil from said surface, at least 0.4 gram of asubstituted benzophenone derivative having the formula wherein X X and Xare each selected from the group consisting of hydrogen, hydroXy, alkyl,allcoxy and halogen.

12. A process for imparting resistance to degradation by ultravioletlight to an organic polymeric shaped structure which comprises the stepsof applying to the surface of said structure a substituted benzophenonederivative having the formula wherein X X and X, are each selected fromthe group consisting of hydrogen, hydroxy, alkyl, alkoxy and halogen;and thereafter heating the treated structure to a temperature above themelting point of said compound and below the melting point of saidorganic polymeric structure. 1 i

13. A process for imparting resistance to degradation by ultravioletlight to "an organic polymeric film which comprises the steps ofapplying to the surface of said film a substituted benzophenonederivative having the formula wherein X X and X, are each selected fromthe group consisting of hydrogen, hydroxy, alkyl, alkoxy and halogen;and thereafter heating the treated film to a temperature above themelting point of said compound and below the melting point of saidorganic polymeric film.

14. A process for imparting resistance to degradation by ultravioletlight to an organic polymeric film which comprises the steps of applyingto the surface of said 14 film a substituted benzophenone derivativehaving the formula OH 7 X2 wherein X X and X areeach selected from thegroup consisting of hydrogen, hydroxy, alkyl, alkoxy and halogen; andthereafter heating the treated film to a temperature of about 115 C. toabout 200 C. for at least 15 seconds. 7

15. A process for imparting resistance to degradation by ultravioletlight to an organic polymeric film which comprises the steps of applyingto the surface of said lm a mixture of2,2-dihydroxy-4,4'-dimethyoxybenzophenone and2,2,4,4-tetrahydroxybenzophenone; and thereafter heating the treatedfilm to a temperature of about 115 C. to about 200 C. for at least 2minutes.

16. A process for preparing polyethylene terephthalate film resistant todegradation by ultraviolet light which comprises the steps of elongatingin at least one direction a polyethylene terephthalate film at least 2times its original dimensions to a thickness of at least 0.5 mil;heating said elongated film to a temperature of about 150-250 C. whilerestricting dimensional change; coating at least one surface of saidfilm with at least 0.4 gram per square meter of each surface of saidfilm thus coated of a substituted benzophenone derivative having theformula wherein X X and X, are each selected from the group consistingof hydrogen, hydroxy, alkyl, alkoxy and halogen from an aqueousdispersion thereof; heating the coated film to a temperature of about C.to about 200 C. for 'a time sufiicient for substantially all of saidsubstituted benzophenone derivative to penetrate the surfaceof said filmto a depth of not more than about 0.1 mil from said surface,

17. A process as in claim 12 wherein the substituted benzophenonederivative is applied to the surface of said structure from a solution.

18. A process as in claim 12 wherein the substituted benzophenonederivative is applied to the surface of said structure from a dispersionin Water.

19. A process as in claim 12 wherein the substituted benzophenonederivative is applied to the surface of said structure as a powder.

20. A process as in claim 12 wherein the substituted benzophenonederivative is applied to the surface of said structure as a melt.

References Cited in the file of this patent UNITED STATES PATENTS1,497,971 Bock June 17, 1924 2,129,131 Hunter Sept, 6, 1938 2,568,894Mackey Sept. 25, 1951 2,614,940 Freyermuth et al. Oct. 21, 19522,693,492 Hoch Nov. 2, 1954 2,757,100 Simril July 31, 1956 2,915,416West Dec. 1, 1959 2,917,402 Sapper Dec. 15, 1959

12. A PROCESS FOR IMPARTING RESISTANCE TO DEGRADATION BY ULTRAVIOLETLIGHT TO AN ORGANIC POLYMERIC SHAPED STRUCTURE WHICH COMPRISES THE STEPSOF APPLYING TO THE SURFACE OF SAID STRUCTURE A SUBSTITUTED BENZOPHENONEDERIVATIVE HAVING THE FORMULA